Vintage Christmas Tree lights

[emeritus]

When I looked a few years ago, I couldn't find anyone selling the type of thin double-insulated single-core flex used on modern mains sets. I have a drum of 600V- rated flexible wire that has a thick insulation comprising a white inner layer and a red outer layer, and used that when extending the set of 20V bulbs from 12 to 16 and converting it from ring to string.

In a couple of the lampholders, the centre contact had pulled right through the hole in the insulation disc, fixed by soldering a small washer to the end of the wire.

[G6Tanuki]

I wonder if you could use an old valve radio mains transformer as an isolation transformer.

Put the mains into one half of the 250-0-250V winding, put the lights across the primary, so you can also use the primary voltage selection things to reduce the voltage, and maybe also use the heater windings to buck the voltage down even further for longer bulb life.

[McMurdo]

one of the perils of using vintage lights is the way the flex is - or isn't - anchored in the lamp holder. Modern series strings have good strain relief, vintage ones often have none. Old brittle pvc cable that's been wound and unwound for decades can soon part company with the holder then you've got a 50:50 chance the bare end will be live.

[matthewhouse]

Originally Posted by emeritus

When I looked a few years ago, I couldn't find anyone selling the type of thin double-insulated single-core flex used on modern mains sets. I have a drum of 600V- rated flexible wire that has a thick insulation comprising a white inner layer and a red outer layer, and used that when extending the set of 20V bulbs from 12 to 16 and converting it from ring to string.

Green tri-rated flexible wire will be the most easily available wire, it has 2 layers of insulation, often a white inner and coloured outer. May not be perfect but will be much safer than the very thin insulation used on older light sets.

[broadgage]

Originally Posted by G6Tanuki

I wonder if you could use an old valve radio mains transformer as an isolation transformer.

Put the mains into one half of the 250-0-250V winding, put the lights across the primary, so you can also use the primary voltage selection things to reduce the voltage, and maybe also use the heater windings to buck the voltage down even further for longer bulb life.

Possibly, but most such transformers are of insufficient current rating.
The HT winding is often less than 50 ma. A common current rating for vintage Christmas lights is either 150ma for 12 lamp sets or 110 ma for 20 lamp sets.

[Joe_Lorenz]

So, considering the load that the transformer must be able to bear with, I'd rather assume one would need a heavy valve amp mains transformer. But why not use the good old variac, provided it is the isolating type?

Joe

[paulsherwin]

You don't need to worry about any of this. An RCD will provide protection against serious electric shock. If you want to reduce the dissipation, use a series diode, or if you don't like the flicker, wire a couple of extra bulbs in series.

We need to keep a sense of proportion about these safety risks. Only a century ago, people were attaching actual candles to the branches of natural pine Christmas trees (which are highly inflammable).

[broadgage]

Years ago I reduced the voltage supplied to Christmas lights by connecting them in series with a 2 foot fluorescent tube.
This had the advantage of reducing the voltage by a roughly constant 50 volts, and providing useful light.
A 2 foot 20 watt lamp for up to about 400ma and a 2 foot 40 watt lamp for up to about 800ma.
The lamp usually started from line voltage, but I added a small transformer for the heaters to ensure reliable operation.

Simpler is just to increase the number of lamps in series, by about 20/25%
For 20 volt lamps, use 15 in series instead of 12
For 12 volt lamps, use 24/25 in series instead of 20.

In years gone by, many attractive Christmas lights were imported, and I suspect designed for 220 volts,extra lamps needed for a reasonable lamp life.
I used to buy 5 similar sets, each of 20 lamps, and modify them to form 4 sets each of 24 lamps, with a few left over for future repairs.

[Joe_Lorenz]

Originally Posted by paulsherwin

Only a century ago, people were attaching actual candles to the branches of natural pine Christmas trees (which are highly inflammable).

Paul, although I am less than a century old I still know this from my childhood! My grandmother refused electric Christmas lights as inappropriate and dangerous (!). I have the candle holders somewhere in the attic.

Joe

[Brigham]

Originally Posted by Joe_Lorenz

... And that's been one of my annual chores, for ages! Usually the last one checked was the culprit. Same procedure as every year. I could never understand why "that bulb" got weird during storage over the summer!

Joe

The last one checked is ALWAYS the culprit.
They are lit after that!

[The Philpott]

Bewildering variety amongst the push-in type, different bases, voltages and wattages. One set of 35 had a dead lamp on retrieval from the loft (it's not just you Joe) prompting a search for obscure 7volt approx 0.8watt......then swapping the base for the correct type.
Ebay to the rescue.

Dad worked at Marconi, and one of the favourite sets for a smallish tree was a mix of red and green gallium phosphide LEDs fed off a transformer, with a yellow one at the top of the tree. Less is more, they looked great. Blue ones were available but prohibitively expensive. Another set of filaments he told me about (but which i don't remember) were made to flash randomly and individually, with Mr.Kipling foil dishes as reflectors. When i moved out i didn't bother with a tree but arranged lights in a triangular pattern on the wall in a darkish corner. Everyone who saw it interpreted it initially as a tree, the brain filled in the gaps- they saw what they expected to see.

Dave

[broadgage]

Christmas lights in which the lamps flash individually used to be available, they consisted of very low voltage lamps wired in parallel from a transformer.

Another style used series connected lamps in which a bimetallic strip short circuited the lamps. A ballast lamp that was always in circuit was essential.

[Station X]

The ones I remember had a flasher lamp which broke the circuit when a bi-metallic strip warmed up and made the circuit when it cooled down. They caused TV and radio interference. The advice was to fit a normal lamp in place of the flasher.

[The Philpott]

I was thinking of those bi-metal flashers yesterday, liked them a lot when I was a kid, now only have one or two spare lamps (red bases on them, presumably to distinguish them from conventional ones with green bases)

I've heard that they wore out quite quickly, the transformer being rated to accommodate around 50% of the lamps being lit at any one time. Unobtainium even second hand now as far as I can tell, rather a shame.

Dave

[The Philpott]

Seems in some sets of 'twinklers' there was only one bimetal lamp, controlling the whole set. Not what I was thinking of. Bound to cause confusion when searching online, because of the ballast lamp type Broadgage refers to.

Dave

[broadgage]

If anyone wants Christmas lights in which each lamp flashes on its own, these may be home made.
E10 base flasher bulbs are still made in various voltages, look on ebay, as are wire ended E10 lamp holders, also from ebay.
Connect in paralell to a suitable transformer, these lamps are usually used on DC from a battery, but work just as well on AC.
Some types are intended for use in torches and will need a reduced voltage for a reasonable lamp life.

Only clear lamps are available, but they may be coloured if desired. For more than about a dozen lamps, use a center tapped transformer and a 3 wire circuit to reduce voltage drop in the wires between transformer and lamps.

[emeritus]

One of my sets for outdoor use has a nominally 24V transformer supplying eight groups of ten series-connected 2.5V bulbs. I bought a pack of 2.5 V flasher bulbs for it at the time, and seven are still working. To counter the short bulb life I selected a couple of wire-wound resistors connected in series to reduce the current enough to still let the flashers operate.

I couldn't find new flasher bulbs in the shops more than ten years ago.

[broadgage]

One less common type of Christmas lights used E10 base neon flicker flame lamps wired in parallel on 240 volt mains.
Sometimes in strings, and sometimes in candle arch lights. More European than UK.
For years, replacement lamps were hard to find, but they are now plentiful and affordable on ebay.
Use little electricity and are IMHO rather attractive.

[Aub]

The vintage set I got from a forum member (can't remember who ) is two sets wired in series, so 24 20volt bulbs, so should greatly extend the bulb life. Mind you, we haven't used them for about 10 years.

Aub